WPF Mediaelement.Position不起作用

What I need is to set the Position property on WPF's MediaElement control. But when I play the video, (either via Play() or through some kind of animation on Opacity) it is is not working at all. It is showing 00:00:00 time, but I would expect it to be set to 00:00:05.

我需要的是在WPF的MediaElement控件上设置Position属性。但是当我播放视频时（通过Play（）或通过Opacity上的某种动画）它根本不起作用。它显示00:00:00时间，但我希望它设置为00:00:05。

I have hard-coded Position value and it is not working at all.

我有硬编码的位置值，它根本不起作用。

Just In case I am going to put all my code I have so u can see the whole animation logic.

以防万一我要把我所有的代码都放在一边，你就可以看到整个动画逻辑了。

Any clue?

任何线索？

  public partial class CrossFadeTransition : UserControl
    {
        DoubleAnimation _doubleAnimationFrontPlayer = new DoubleAnimation();
        DoubleAnimation _doubleAnimationBackPlayer = new DoubleAnimation();

        Storyboard _sb1 = new Storyboard();
        Storyboard _sb2 = new Storyboard();

        public TimeSpan Duration = TimeSpan.FromSeconds(2);
        public Dictionary<string, Position2D> PlayerPosition { set; get; }

        public CrossFadeTransition()
        {
            InitializeComponent();

            Player1.LoadedBehavior = MediaState.Manual;
            Player1.UnloadedBehavior = MediaState.Stop;

            Player2.LoadedBehavior = MediaState.Manual;
            Player2.UnloadedBehavior = MediaState.Stop;

            PlayerPosition = new Dictionary<string, Position2D>();

            PlayerPosition.Add("Player1", Position2D.Front);
            PlayerPosition.Add("Player2", Position2D.Back);

        }
        Position2D positionPlayer1;
        Position2D positionPlayer2;

        public void Stop()
        {
            if (Player1.IsEnabled)
                Player1.Stop();

            if (Player2.IsEnabled)
                Player2.Stop();

        }

        public void Start(Uri uri, int? position)
        {
            try
            {
                positionPlayer1 = PlayerPosition["Player1"];

                positionPlayer2 = PlayerPosition["Player2"];

                if (positionPlayer1 == Library.Position2D.Back)
                {
                    Player1.Source = uri;
                    if (Player1.IsEnabled)
                        Player1.Stop();

                    Player1.Position = TimeSpan.FromSeconds(5); // IT IS NOT WORKING !!!

                    Player1.Play();

                }

                if (positionPlayer2 == Library.Position2D.Back)
                {
                    Player2.Source = uri;
                    if (Player2.IsEnabled)
                        Player2.Stop();

                    Player2.Position = TimeSpan.FromSeconds(5); // IT IS NOT WORKING !!!

                    Player2.Play();

                }



                _sb1.Children.Clear();
                _sb2.Children.Clear();



                if (positionPlayer1 == Position2D.Front)
                {
                    _doubleAnimationFrontPlayer.From = 1;
                    _doubleAnimationFrontPlayer.To = 0;
                    _doubleAnimationFrontPlayer.Duration = new Duration(Duration);

                    PlayerPosition["Player1"] = Position2D.Back;
                }
                else if (positionPlayer1 == Position2D.Back)
                {
                    _doubleAnimationFrontPlayer.From = 0;
                    _doubleAnimationFrontPlayer.To = 1;
                    _doubleAnimationFrontPlayer.Duration = new Duration(Duration);

                    PlayerPosition["Player1"] = Position2D.Front;
                }

                if (positionPlayer2 == Position2D.Front)
                {
                    _doubleAnimationBackPlayer.From = 1;
                    _doubleAnimationBackPlayer.To = 0;
                    _doubleAnimationBackPlayer.Duration = new Duration(Duration);

                    PlayerPosition["Player2"] = Position2D.Back;
                }
                else if (positionPlayer2 == Position2D.Back)
                {
                    _doubleAnimationBackPlayer.From = 0;
                    _doubleAnimationBackPlayer.To = 1;
                    _doubleAnimationBackPlayer.Duration = new Duration(Duration);

                    PlayerPosition["Player2"] = Position2D.Front;
                }

                _sb1.Children.Add(_doubleAnimationFrontPlayer);
                Storyboard.SetTargetProperty(_doubleAnimationFrontPlayer, new PropertyPath("(Panel.Opacity)"));
                Storyboard.SetTarget(_doubleAnimationFrontPlayer, Player1);
                _sb1.Completed += _sb1_Completed;
                _sb1.Begin();

                //
                _sb2.Children.Add(_doubleAnimationBackPlayer);
                Storyboard.SetTargetProperty(_doubleAnimationBackPlayer, new PropertyPath("(Panel.Opacity)"));
                Storyboard.SetTarget(_doubleAnimationBackPlayer, Player2);
                _sb2.Completed += _sb2_Completed;
                _sb2.Begin();

            }
            catch (Exception)
            {

                throw;
            }
        }

        void _sb2_Completed(object sender, EventArgs e)
        {
            _sb2.Completed -= _sb2_Completed;

            Debug.WriteLine("Player2 COMPLETED " + DateTime.Now.TimeOfDay);

            if (positionPlayer2 == Position2D.Front)
            {
                Player2.Stop();
            }
        }

        void _sb1_Completed(object sender, EventArgs e)
        {
            _sb1.Completed -= _sb1_Completed;

            Debug.WriteLine("Player1 COMPLETED " + DateTime.Now.TimeOfDay);
            if (positionPlayer1 == Position2D.Front)
            {
                Player1.Stop();
            }
        }
    }

I have tried to do like

我试着这样做

Player2.Play();
Player2.Pause();
Player2.Position = TimeSpan.FromSeconds(5); // IT IS NOT WORKING !!!
Player2.Play();

But no joy...

但没有快乐......

1 个解决方案

#1

I found some solution. It is not completely ideal because sometimes it shows the first video frame, but at least it is working.

我找到了一些解决方案它并不完全理想，因为有时它会显示第一个视频帧，但至少它正在工作。

We need those events where we can apply new Position.

我们需要那些可以申请新职位的活动。

void Player2_MediaOpened(object sender, RoutedEventArgs e)
{
     Player2.Position = new TimeSpan(0, 0, 7);
}

void Player1_MediaOpened(object sender, RoutedEventArgs e)
{
    Player1.Position = new TimeSpan(0, 0, 7);
}

We have to close Mediaelement like this.

我们必须像这样关闭Mediaelement。
```
Player1.Stop();
Player1.Close();
Player1.Source = uri;
Player1.Play();
```

Have fun! (beer)

玩的开心！（啤酒）

#1